49ers RG Garnett plays plenty in long-awaited return

Sa Fransisco 49ers offensive lineman Joshua Garnett (65) warms up before practice on the practice field in Levis Stadium in Santa Clara on Wednesday, August 2, 2017.

Photo: Nicole Boliaux / The Chronicle

HOUSTON — The competition to be the 49ers’ starting right guard continued Saturday and it appears Mike Person and Joshua Garnett are the frontrunners.

For the second straight week, Person started at the position, but Garnett relieved him and played the second series, which was the final drive for the first-team offense in the second preseason game against the Texans.

Garnett, who hadn’t played in a game since Jan. 1, 2017, due to knee injuries that forced him to miss last season and the preseason opener, played deep into the third quarter. He was replaced by Jonathan Cooper, another potential candidate for the starting spot.

“It’s definitely a great feeling to get back out there with the boys and mix it up,” Garnett said. “Got a lot of things to improve on, but I felt good just being out there … I feel like the knee feels great - didn’t have any hiccups. So I feel like that’s a big steppingstone - milestone - for me.”

Garnett returned to practice last week and took the first-team snaps in their final session Thursday while Person was the second-team center.

After three training-camp practices, Garnett missed the next two weeks with an issue in the same knee on which he had surgery last year. Head coach Kyle Shanahan expressed surprise Garnett wasn’t practicing early in training camp, and Garnett said that was due to a “lack of communication” on his part.

“We got everything squared up,” Garnett said. “I’ve been back out there and played half the game today. So we’re definitely all on good terms and we’ve definitely got a good plan going.”

New rule: The 49ers were called for two helmet-lowering penalties in the final two minutes of the second quarter after they had one infraction of the NFL’s new rule in the preseason opener.

On a punt, gunner Raheem Mostert was flagged after stopping returner Tyler Ervin for no gain, although Mostert appeared to have his helmet to the side when he made contact. Later, defensive end Jeremiah Attaochu was assessed the 15-yard penalty after lowering his head on a pass-rush.

Shortly after the game, cornerback Richard Sherman, said, via Twitter: “Welcome to NFL football. More offense is all they want. That’s why the calls go the way they do.”

Said Mostert: “I guess they thought it was bad form. I thought it was good technique by me.”

Sherman close: Sherman, who has a hamstring injury, went through warm-ups in uniform but did not play, which suggests he will be available for the third preseason game Saturday in Indianapolis.

Sherman, who missed the offseason program while recovering from a torn Achilles, participated in individual drills during joint practices with the Texans on Wednesday and Thursday. He hasn’t played in a game since Nov. 9.

Defensive coordinator Robert Saleh said Wednesday that Sherman was lobbying to play Saturday.

“He wants to be with his teammates, and that’s the type of man he is,” Saleh said. “So he’ll get his opportunity, but we’re trying to be as smart as we can with it.”

Eric Branch has worked at the San Francisco Chronicle since 2011 as the 49ers beat writer. Before that, he covered the 49ers for the Santa Rosa Press Democrat in 2010. Since he began his career in journalism in 1997 in Logansport, Ind., he’s covered events ranging from archery tournaments to the NCAA Men’s Basketball Tournament.